There have been deaths reported in Tonga although other Pacific islands have not been impacted by the Pacific tsunami that hit Samoa and American Samoa.
Tongan officials say there have been reports of 10 deaths on the island of Niuatoputatu, which borders Samoa, the ABC said.
New Zealand Foreign Minister Murray McCully said the northern tip of Tonga had been impacted by the tsunami.
"That is where the airport is out of commission at the moment, there are rocks all over it," McCully told reporters in Wellington.
"There was an attempt being made by the Tongan government to get a flight across the top to inspect damage."
McCully said there were reports of five deaths on the northern island of Tonga.
"There are, obviously, concerns about other casualties there and until we are able to get more information from there I can't go further than that."
Australia's Department of Foreign Affairs and Trade (DFAT) said it was aware of reports of damage, death and injuries in the Niua islands in Tonga.
The United Nations said there had been no significant damage reported in Tonga.
"High sea levels in Ha'apai have affected low lying areas in Lifuka from Pangai to Hihifo side and also the areas between Tailulu college and the Hospital at Hihifo," a report from the UN Office for the Coordination of Humanitarian Affairs (OCHA) said.
"The hospital is reported to be flooded.
"Water has reached the road at Hihifo although it appears unlikely it will breach the road."
Other countries in the Pacific do not appear to have been affected.
"The reports from Tokelau have been that there's been no serious damage so that's obviously good news. Being low lying that was, obviously, a concern," McCully said.
"We've also been seeking information about the northern group of the Cooks which are again low lying but we've got no information there about damage."
The OCHA said waves had reached the Lau Group, Rotuma, Vanua Levu and Taveuni islands in Fiji, but no damage had been reported.
"Residents of Vanabalavu (Lau Group) reported that a series of 10 waves entered the lagoon during low tide but did not breach the sea wall."
The OCHA said reports had been received that Kiribati and the Federated States of Micronesia had not been affected by the tsunami.
"... The Marshall Islands have seen some high wave action but have not been affected by the tsunami or the current tropical storm."
Authorities, at the moment, have no concerns about Australians who may be in Tonga, Foreign Minister Stephen Smith said.
"I have spoken to our high commissioner in Tonga and the level of damage is such that we're not concerned at this stage about any Australians," Smith said.
Smith said the advice was that Australians in Pacific islands such as Niue, Fiji, Noumea, New Zealand or Nauru had not been harmed.
A spokesman for McCully earlier told NZPA there were "bigger than usual" waves in the Cook Islands, with swells up to one metre being reported in Rarotonga.
Niue was reasonably safe because it was high, the spokesman said.
"Reasonable" sized waves had been seen and the earthquake that sparked the tsunami was felt there.
Neither Vanuatu, Kiribati, New Caledonia nor the Solomon Islands had reported high waves.